EA000316B1 - Thread feed device for elastic yarn - Google Patents

Abstract

1. Thread feed device for elastic yarn to feed yarn to loop-forming places in which the thread consumption fluctuates markedly with time for raschel and knitting machines, in particular for flat-knitting machines (4) comprising - a thread-feed device to define the thread path, determined by thread-guiding elements, - a thread-feeding wheel arranged on the thread path so as said wheel can be defined by a thread and which serves for conveying the yarn in predetermined regimes, - an electrical motor, having a low inertia, rigidly-connected to the thread-feeding wheel, a tension sensor for monitoring of the thread tension and said sensor has a thread-guiding element which enables at least a slight deviation along the measurement path, - a regulator via the motor, driving the thread-feeding wheel is monitored by signals, transmitted by the sensor device so as the thread tension is regulated with setting to the nominal value, - a thread store for intermediate thread storing and, if necessary, for repeated take-up, fed by the thread-feeding wheel and not consumed in the loop-forming places, and for feeding the thread, needed in the loop-forming places, but which was not fed by the thread-feeding wheel; characterized in that the thread store (19) is functionally separated from the sensor (22) device, and all thread path is not tensed, the tension sensor (22), having the measurement path substantially equal to zero, and the thread store (19) takes the form of a substantially straight section between the thread-feeding wheel (11) and the loop-forming place, on which the elastic yarn (2) enables to free tension, and the thread, stored in the thread store has a rigidity coefficient, which is less than the predetermined given value, equal to the ratio of maximum change of strength to the length of thread, which can maximum store the thread store. 2. Use of the thread path of the thread feed device for elastic yarn provided for the thread feed to the loop-forming places with the thread consumption fluctuating markedly with time in raschel and knitting machines, in particular for flat-knitting machines (4) comprising - a thread-feed device to define the thread path, determined by thread-guiding elements, - a thread-feeding wheel arranged on the thread path so as said wheel can be defined by a thread and which serves for conveying the yarn in predetermined regimes, - an electrical motor, having a low inertia, rigidly-connected to the thread-feeding wheel, - a tension sensor for monitoring of the thread tension and said sensor has a thread-guiding element which enables at least a slight deviation along the measurement path, - a regulator via the motor, driving the thread-feeding wheel is monitored by signals, transmitted by the sensor device so as the thread tension is regulated with setting to the nominal value, as the thread store for receiving, intermediate storing and feeding of the thread, which, with marked fluctuations of the thread tension due to inertia moments of the thread-feeding wheel and the motor is fed excessively or insufficiently, compared to the thread consumption in the knitting machine., - a straight section is formed between the thread-feeding wheel (11) and the loop-forming place, on which the elastic yarn (2) enables to free tension, and the thread, stored in the thread store has a rigidity coefficient, which is less than the predetermined given value, equal to the ratio of maximum change of strength to the length of thread, which can maximum store the thread store. 3. Thread feed device of Claim 1, characterized in that the tension sensor (22) is provided with a mobile element (25), having the maximum measurement path, which, at least, by one order less, than the thread length (2) to be intermediately stored 4. Thread feed device of Claim 1, characterized in that the tension sensor (22) is provided with a spring catch (51), curvature of which is determined by the thread tension and which connected with a converter for measuring the curvature. 5. Thread feed device of Claim 5, characterized in that the converter is an electromechanical converter with a small required deviation. 6. Thread feed device of Claim 1, characterized in that the tension sensor (22) is constructed separately from the rest of feed device. 7. Thread feed device of Claim 1, characterized in that the tension sensor (22) has a separate suspension made so to eliminate coupling with the vibrating movement of the knitting machine. 8. Thread feed device of Claim 1, characterized in that it is protected from the vibrating movement of the knitting machine. 9. Thread feed device of Claim 1, characterized in that it is provided with the regulator (24) to monitor the driving means in all regimes of operation, independently of knitting machine (4) speed, based on the thread tension, determined by the tension sensor. 10. Thread feed device of Claim 9, characterized in that the tension regulator (24) is a proportional-integral regulator. 11. Thread feed device of Claim 9, characterized in that the tension regulator (24) is a proportional-integral-differential regulator. 12. Thread feed device of Claim 1, characterized in that the driving means (9) is a step engine. 13. Thread feed device of Claim 1, characterized in that the driving means (9) is an electrical motor with a disc rotor. 14. Thread feed device of Claim 1, characterized in that the driving means (9) and corresponding control means (tension regulator 24) are made providing the operation of the driving means (9) un two directions of rotation. 15. Thread feed device of Claim 1, characterized in that the thread-feeding wheel is formed by radially-arranged wire clamps (13) are fastened on the hub (12) each said clamp has a section (16), passing essentially in axial direction for winding the thread, wherein each wire clamp (13) has two spokes (14, 15), on which the axial section (16) rests. 16. Thread feed device of Claim 1, characterized in that the thread path from the thread-feeding wheel (11) to the guide machine element (6) of the knitting machine (4) passes essentially in one direction. 17. Thread feed device of Claim 1, characterized in that for determining the present value of the thread tension two independently-operated tension sensors (22, 22) are provided and situated at a certain distance from each other along the thread path. 18. Thread feed device of Claim 1, characterized in that a filter (29) is arranged between the tension sensor (22) and connected with it the tension regulator (24) 19. Thread feed device of Claim 1, characterized in that the filter (29) suppresses frequency interference. 20. Thread feed device of Claim 1, characterized in that the filter (29) is provided with compensating means to suppress interference signals. 21. Use of the thread feed device according to one or several preceding Claims for flat-knitting machine.

Description

The invention relates to a feeder filament with signs of the restrictive part of claim 1 of the claims, which serves to supply elastic threads, tapes, strands, etc.

The yarn feeders in knitting and knitting machines perform the task of feeding the yarn with the required tension and in the desired quantity to the places of looping at the right time. This is especially true for elastomeric yarn or other elastic threads, which are treated most often in combination with hard, i.e. essentially non-elastic yarn (core yarns), in more or less elastic knitted fabrics. In this case, the tension of the elastomeric yarn substantially determines the neck and dimensional stability of the knitted fabric being created. Fluctuations in the tension of the supplied elastomeric yarn can lead to a significant reduction in the quality of the knitted fabric being created, in particular, if they arise systematically from one stitch row to another stitch row.

Due to the high elongation of the commonly used elastomeric yarn, reaching 600% of the main length, a suitable yarn feeder is required to maintain the yarn tension constant, which delivers the correct amount of yarn regardless of the specific yarn consumption and regardless of the initial tension of the yarn reel.

This applies in particular to knitting machines with drastically changing and, at least temporarily, very high yarn consumption, for example, flat knitting machines and other knitting machines in which a single yarn feeder provides a number of needles. In flat knitting machines, the needles forming loops arranged in one row or in several rows are fed by one or several threads to be used with the help of a yarn feeder which moves linearly along the row of needles. In this case, the threads are fed using the yarn feeder, which is located on the side of the yarn guide so that it moves from the yarn feeder or, respectively, towards it. Obviously, the required amount of yarn fed during both working phases is very different. To this is added the fact that at the points of change in the direction of movement between the working phases the yarn consumption is zero, and during the transition from the working phase of retraction from the yarn feeder to the working phase, approaching the yarn feeder occurs a short working period of time during which the thread moves back .

For applications with a time-varying flow rate of threads, a yarn feed device known from DE 36 27 731 C1 has been developed, which has a yarn feed wheel driven by a stepper motor. It feeds the thread reeled from the reel through the thread brake to the appropriate looping point.

In this case, the thread supplied by the thread-feed wheel passes through the eye located at the end of the lever, which is installed at the other end with the possibility of rotation, and the eye represents the point of change of direction at which the thread is deflected at an acute angle. To install a constant tension of the thread on the swivel arm from the DC motor transmit a constant torque. In addition, the pivot arm is connected to a position sensor, which measures its pivot position and accordingly controls the stepping motor. Thus, the pivoting lever acts as a thread accumulator for intermediate accumulation of the thread, which was not taken as a looping point, which, however, was filed due to the inertia and control characteristics of the stepper motor. In addition, it serves to adjust the tension of the thread, as well as to measure the available stock of the thread in conjunction with a sensitive device.

This yarn feeder is only limitedly suitable for feeding elastic yarn, and the swivel arm is too insensitive to control the tension.

Due to the elasticity of the yarn, the pivot arm during operation reaches its extreme positions (stops), and at these moments the thread tension is out of control.

The improved filament feeding device for wavy and other shaped yarn, known from DE 38 20 618 C2, has two rotating in opposite directions under the action of the drive of the thread-giving wheels, around which the yarn to be fed is repeatedly wound around eight. As the thread accumulator for the intermediate accumulation of the thread, which is temporarily not taken in places of looping, there is a carrying lever, which has an eyelet at one end, on which a rotational moment acts in a given direction of rotation. The yarn passes through the eyelet located at its end at an acute angle and, for intermediate accumulation, it is laid on the fingers or the stand located along the circumference described by the lever.

On the fingers forming the intermediate accumulator or the pillars, as well as in the ear penetrated at an acute angle, friction forces arise that affect the course of the yarn.

From DE 42 06 607 A1, a yarn feeder is known for simultaneously feeding two yarns to a knitting machine, in which the yarn feed wheel is driven by the electric motor with a disk rotor. At least one thread passes from the thread-feed wheel through the longitudinal hole of the helical spring, wound in the form of a cone or in the form of a looped tube. A permanent magnet and a Hall sensor for measuring the amount of deflection of the helical spring are provided on the support holding the coil spring rotatably at one end. On its basis, the electric motor with a disk rotor is adjusted, so that the nominal position of the coil spring is established in a stationary position. In this position, the thread passes through the hole of the coil spring on the side, adjacent to its inner wall. The coil spring serves as a spring and damping element that provides a certain intermediate accumulation of the supplied thread.

Finally, from US-PS 38 58 416 a yarn feeder is known, which is suitable for knitting machines with a substantially constant yarn consumption and for feeding hard yarn. The yarn feeder has an electric motor with a rotational speed controlled by an applied voltage, which with the help of a corresponding yarn feed wheel winds the yarn from a bobbin and feeds it to the corresponding looping point through a yarn tension sensor. In addition, a nominal value sensor is provided, which is connected via a switch and optional switching devices to the regulator nominal value input. The regulator receives, through a switch, a signal characterizing the tension of the thread at its input of the real value and controls the electric motor accordingly. In addition, rotational speed sensors are provided on the electric motor and on the knitting machine, which can be connected to the nominal value input and the actual value input of the regulating device at the corresponding switch position. The switch allows switching from a mode with a constant adjustable tension of the thread to the mode of feeding a certain amount of thread. For each looping point of a circular knitting machine, a corresponding yarn feeder is provided, so that the quantity of yarn to be fed corresponds to the yarn consumption of one looping point. The speed of movement of the thread is correspondingly low.

Measures for intermediate accumulation that may arise as a result of the inertia or characteristics of an electric motor that are too long or that are suddenly needed to feed lengths of the thread have not been taken.

Such a yarn feeder is not suitable for feeding elastic yarn in knitting machines with a high speed of moving yarn and sudden changes in speed that occur in flat knitting machines.

On this basis, the object of the invention is to provide a yarn feeder with which elastic yarns can be fed into knitting machines at high speeds that can change dramatically, with essentially constant yarn tension.

This problem is solved using the filing device with the signs of claim 1 of the claims and the method according to claim 21 of the claims.

The yarn feeder is a speed and tension regulator for yarns, ribbons, etc., which, due to the low inertia moments of the drive unit and the yarn feed wheel, can be adapted to rapidly changing yarn consumption parameters. In feed phases, with full thread consumption, the yarn speeds reach several meters per second (6 m / s). Between the feed phases there are phases of sudden stops and / or phases of reverse movement. The provided yarn hopper allows the amount of yarn arising in the transition between the above phases to be received or re-delivered, without essentially changing the yarn tension. In this case, a substantially zero stroke sensitive device serves as a tension sensor for monitoring the tension of the thread. The measuring stroke of the sensitive device, which is vanishingly small compared to the amount of the thread to be intermediate accumulated, makes it possible to adjust the tension of the thread almost independently of the acceleration forces of any moving parts of the sensitive device. Thus, the sensitive device has a small mass, is highly dynamic and does not have the opposite reaction. The thread accumulator and the sensing device are functionally separated from each other. Specifically, this is achieved by the fact that the measuring stroke of the sensitive device, supported by a small one, is directed essentially perpendicular to the direction of passage of the thread.

Another aspect of the invention is that the entire path traveled by the thread is inelastic, i.e. All thread guide elements are fixed. Due to this, it is possible to eliminate the oscillatory processes of the elements of the machine, which can have the opposite effect on the tension of the thread. The only elasticity or ductility available in the system is represented by its own elasticity of the thread, with the help of which a thread accumulator is created on a specially selected section of the path.

Due to the fact that the thread accumulator is made in the form of a section of the path between the thread-giving wheel and the looping point, on which the elastic yarn is carried out with the possibility of free stretching, a yarn accumulator is created, which accepts the section of yarn to be accumulated without friction. This is achieved due to the fact that the segment of the path that serves as the accumulator of a thread has such a length that the coefficient of elastic rigidity formed with the corresponding yarn does not reach the limit value. This limit value is equal to the ratio of the maximum change in force to the maximum yarn length accepted by the accumulator. The length of the thread forming the accumulator is preferably more than half a meter.

When the filing device is located on the side, i.e. essentially, in the continuation of the machine-forming row of needles, acting as a thread accumulator, the distance between the thread-feed wheel and the knitting machine thread guide periodically changes its length in accordance with the working steps of the knitting machine. Thus, the thread accumulator changes its capacity. This is particularly favorable for the ratios in the flat knitting machine at the end of the retraction phase, in which the yarn feeder moves away from the yarn feeder, due to the fact that the greatest deceleration of the thread occurs at the end of the retraction phase. During the retraction phase, the number of threads is fed, which almost corresponds to double consumption of the thread. When the yarn feeder reaches the point of changing the direction of movement and first stops at it, the thread consumption will suddenly drop to zero. The release of elastic yarn, caused by the inertial coasting of the drive unit, can easily be taken up with its maximum yarn accumulator, without causing a change in the yarn tension.

In contrast, in the opposite direction of the change in direction of movement, only a relatively small change in the yarn feed rate occurs, which is easily accepted by the yarn collector shortened in this position.

Thus, depending on the current position of the yarn feeder, the length of the yarn accumulator of the yarn feeder ensures good matching of the yarn accumulator capacity with the occurring deviations of the yarn feed from the actual yarn consumption, in particular, in the overrun phases.

Preferred was the fact that elastic yarn to measure its tension is rejected in the sensitive device only slightly. A blunt filament angle is formed, which is preferably more than 165 °. Although the forces to be measured become very small because of this, the friction that arises here is so small that its influence becomes insignificant. This is particularly important for elastomeric yarns.

The accuracy of the yarn feeder is increased if the sensitive device (tension sensor) has a negligibly small maximum stroke that is at least one order less than the length of the yarn segment to be accumulated. This achieves the fact that a piece of yarn is accepted only by the accumulator of the thread, and not by the sensitive device. This is achieved, for example, if the element in contact with elastic yarn has a maximum stroke of less than 2 mm.

Structurally, the sensitive device can be separated from the yarn feeder. Due to this, it is possible to position the sensitive device as close as possible to the places of looping, respectively, to the yarn guide. Thereby, changes in tension occurring in places of looping are quickly measured and quickly eliminated. In addition, the regulation accuracy is improved if the sensitive device has a separate suspension, to which the vibrations of the knitting machine are not transmitted.

In addition, it is preferable that the yarn feeder is also designed so that it is separated from the knitting machine and / or vibrations are not transmitted to it.

The drive device is controlled by the regulating device depending on the thread tension. To prevent erroneous control, it is advisable that the regulating device in all operating modes work independently of the speed of the knitting machine. With this, it is possible to achieve the fact that once the tension of the thread is set remains constant even with a change in the speed of the knitting machine, the stroke of the yarn feeder, the knitting pattern or other influencing quantities. This avoids incorrect adjustments that may otherwise occur when the specified operating parameters are changed. In this case, the regulating device can be a proportional-integral or proportional-integral-differential controller.

Having a sufficiently large size and, in particular, a thread storage device coordinated in its capacity with the corresponding position of the yarn feeder, it is possible to use a stepping motor as a drive device for the yarn feed wheel. This stepping motor, made preferably in the form of an electric motor with a disk rotor, has a high dynamics, however, the specified maximum values cannot be exceeded during acceleration and deceleration. The corresponding mismatch or excess yarn feed is compensated by the yarn hopper.

The return feed of the thread at the point of change in the direction of movement of the yarn feeder from the phase of its retraction from the thread-feed wheel to its return phase can be compensated if the control device (control circuit) and the drive device are designed so that the thread-feed wheel can move in both directions of rotation.

In addition, it turned out to be preferable to hold the yarn as far as possible without changing the direction, so that it has the same tension over its entire length.

As an alternative solution, the determination of the tension of the thread can be made using two or more sensitive devices installed at different points in the path of movement of the yarn. From the signal output by sensitive devices, a signal is generated of the actual value for the regulating device.

At least one filter can be located between the sensing device and the regulating device, which does not allow interference frequencies to the regulating device as a low-pass filter or as a band-pass filter. Alternatively, rejection band-pass filters or the like can also be used.

Compensating means for suppressing interference signals can be provided, for example, directly on a sensitive device. Such compensating means are performed, for example, in the form of an identical measuring system, which is not affected by the yarn. With an appropriate setting and high own attenuation, the difference between the signals generated by both sensitive devices characterizes the thread tension.

The invention is illustrated below by the example of execution using the drawings, which depict:

figure 1 - feeder yarn in a flat knitting machine in the form of a schematic diagram;

figure 2 is a simplified view of the feeder yarn of figure 1 in different working phases, in the form of a schematic diagram;

figure 3 is a timing diagram of the change in the tension of the thread in the feeder yarn of figure 1 and 2 in comparison with the known from the prior art feeder yarn;

figure 4 is an embodiment of a sensitive device for determining the tension of the thread in cross section in schematic form.

Figure 1 shows the device 1 feed thread, which brings the elastic thread 2 (elastomeric yarn) from the reel 3 to the flat knitting machine 4, which is shown only conventionally and is represented by cutouts with loop-forming needles 5 and yarn thread 6. The device 1 feed thread contains the device 7 winding the yarn, which provides the winding of the thread 2 from the reel 3 and feed to the yarn guide 6.

The yarn rewinder 7 has a housing 8 within which a stepper motor 9, not shown in detail, is schematically indicated in FIG. 2. The stepper motor 9 is designed as an electric motor with a disk rotor that can be accelerated and decelerated in short periods of time.

On the drive shaft of the stepping motor 9 coming out of the housing 8, the thread feed wheel is rigidly fixed with the possibility of rotation

11. It has a hub 12, from which, in general, six wire brackets 13 extend at the same distance from each other in the radial direction.

Wire staples 13 each have two radially positioned spokes 14, 15, as well as a supporting section 16 connecting them. On the supporting sections there is a thread 2 that spans the thread feed wheel 11 a small number of times.

From the thread-feed wheel 11 to the yarn feeder 6 there is a thread drive 19, which thread 2 passes essentially along a straight path. This path is essentially parallel to the direction indicated in figure 1 by the arrow 21 of the reciprocating movement of the yarn feeder 6.

Inside the yarn accumulator 19, a sensing device 22 is installed for tensioning the moving yarn 2, which through the output line 23 is connected to the regulating device 24 indicated only schematically (FIG. 2). The sensing device 22 generates an electrical signal characterizing the tension of the thread.

The sensing device 22, which has a movably mounted element 25 with a very short stroke, is configured as a tension sensor with a substantially zero stroke. It deflects the thread 2 in the vertical direction, which on both sides of the element 25 passes through two counter supports 26, 27, preferably made in the form of eyes. The junction line contour 26, 27 determines the direction of movement of the thread 2, which runs perpendicular to the direction of deflection of the element 25. At the same time, the lateral deviation of the thread 2 in the sensitive device 22 is so small that the obtuse angle passed by the thread 2 with the top on element 25 is more than 165 °.

Sensitive device 22 contains a strain gauge that converts various deviations of element 25 caused by fluctuations in the tension of the thread into electric signals, which are fed to the regulating device 24. At the same time, movement of element 25 is so small that it does not cause any noticeable change in the tension of the thread

2

As shown in FIG. 2, a filter 29 may optionally be installed between the sensing device 22 and the regulating device 24, which suppresses interference frequencies. They can be caused by the vibration of a sensitive device 22 or by pickups. However, both the sensitive device 22 and the yarn rewind device 7 are installed so that their oscillations are insignificant.

As follows from figures 1 and 2 in conjunction with the preceding description, the entire path of the passage of the thread sustained, if possible, without deviations from the straight. From the reel 3 thread 2 passes without changing the direction of movement and without braking, i.e. without a thread brake, onto and from the thread-feeding wheel 11 without significant change in the direction of movement to the yarn guide 6. The thread guide 6 leads the elastic thread 2, following in each direction of movement, behind the rigid rod thread 31, to the needles 5.

The yarn feeder 1 described above operates as follows:

In FIG. 2, the flat knitting machine shown as an example is represented by a series of 32 loop-forming needles 5. During the knitting process, the needles 5 are deflected and returned again as a traveling wave, while the yarn feeder 6 is moved back and forth in the direction of the arrow 21. In this case, the yarn feeder 6 moves, for example, from close end position 33 to remote end position 34, and the yarn feeder 1 must supply a quantity of yarn that is more than twice the distance traveled by the yarn feeder 6.

The yarn tension arising in the process of knitting is shown in FIG. The beginning of the movement of the yarn feeder 6 th end position 33 is indicated in figure 3 in the upper diagram I by the position 41. At the time of the start of movement, the tension of the thread 2 is still in the tolerance field, which can be measured by the sensing device 22. The stepper motor 9 and the yarn feed wheel 11 are first at rest. However, the suddenly started consumption of yarn is first covered by a yarn hopper, while the yarn tension initially increases slightly.

The increasing tension of the thread causes the regulating device 24 to accelerate the stepping motor 9. The thread giving the wheel 11 winds the thread 2 from the reel 3 and feeds it to the drive 19 of the thread, the length of which increases with the yarn feeder 6.

After a certain time of establishing the process, ending at point 42, the thread-feeding wheel 11 will deliver just the amount of yarn consumed by the flat knitting machine 4 and the quantity of yarn accepted by the hopper 19 of the thread.

When the yarn feeder 6 reaches the remote end position 34, it suddenly stops. This moment of time in figure 3 in the diagram I is indicated by the position 43. In the time interval to the point 44, the regulating device stops the stepping motor 9 and thereby the yarn feed wheel 11, while the thread tension is insignificant, i.e. within tolerances, decreases. If the tolerance field is chosen to be very narrow, then during the stop of the yarn feeder 6 in its remote end position 34, the required thread tension is again created by reverse rotation of the thread-feeding wheel 11. Due to the wiring of the elastic thread 2 between the reel 3 and the thread guide wheel 11 without a thread brake, reverse feeding is possible without the risk of interfering with the passage of the thread.

When the reverse movement of the yarn feeder 6 begins at point 45 of FIG. 3, the phase of the dead zone first indicated in FIG. 2 passes at 46, during which there is no thread consumption at the loop formation points, however, as a result of the beginning reverse movement of the yarn feeder 6 freed up. It is received by the accumulator 19 of the thread and, in accordance with the need, is compensated for by briefly returning the thread-feeding wheel 11. The yarn consumption that starts then when moving to the near end position 33 is noticeably lower than in the opposite movement to the far end position 34. Therefore, the thread feeder 1 without problems feeds the appropriate amount of yarn into the shortening accumulator 19 of the thread.

Starting from time 47, in which the tension of the thread reaches its upper limit value, it is kept constant throughout the return path of the yarn feeder 6 until it reaches its near end position 33 at point 48. A slight inertial run-down of the thread feed wheel 11 may lead to a time point 49 to a slight decrease in the tension of the thread.

In Fig. 3, the course of changing the tension of the thread, achieved with the help of the device 1 for feeding the thread (diagram I), is opposed to the course of changing the tension of the thread, achieved with the help of the device for feeding the thread (diagram II) known from the prior art according to DE 36 27 731 C1. It has, as indicated in the introductory part of the description, changing the direction of movement of the thread, a pivoting lever as a thread accumulator. Its mass and friction influence the tension of the thread and the regulator. As follows from diagram II with the same reference points in time 41-49, the phase of the transition process for tensioning the thread during a direct course (from 41 to 42) is significantly longer, with peaks of tension values that can lead to breakage of the thread. Even during the reverse stroke between time points 45 and 47, a transient process occurs, which leads to an increase in the tension of the thread, as a result of which an uneven knitted fabric is formed.

In particular, the deviations of tension are especially different on the right and left edges of the knitted fabric, which adversely affects the quality of the binding. In contrast, the tension of the thread with the device 1 feed thread, according to the invention, shown in diagram I, is essentially constant, and, in particular, on both edges of the knitted fabric (near and far end position 33, 34) are identical or almost identical tension threads.

As shown in FIG. 2 by dashed lines, in addition to one sensitive device 22, another sensitive device 22 'can be provided, which measures the tension of the thread. It measures the thread tension elsewhere in the path of the thread. The control device generates, for example, the average value of the signals of both sensitive devices 22, 22 'and takes this average value as the actual value of the thread tension. Thus, it is possible to minimize the effect of interference.

FIG. 4 shows a modified embodiment of the sensing device 22a. The sensing device 22a has a first element 25 containing a spring tongue 51, on the ceramic support 52 for the thread of which the thread 2 passes. The strain gauge 53 converts the bending of the spring tongue 51 into an electrical signal. A similar element 25 'also contains a ceramic support 52' for the thread and a strain gauge 53 '. Both elements 25, 25 'are damped above the critical value, so that they do not oscillate after shock excitation. The element 25 'does not have contact with the thread 2 ×! The output signal of the sensing device is equal to the difference between the signals output by both strain gauges 53, 53'. Tagam minimizes the effect of interference caused by jolts and / or vibrations.

Created device 1 filament yarn for elastic yarn for knitting machines with highly time-varying and periodically high yarn consumption, which is made in the form of a regulator of the movement of the thread. The yarn feeder 1 has a thread-feed wheel 11 covered by a small number of turns of the yarn to be fed 2, which feeds the thread 2 into a drive 19 of the thread located between the knitting machine and the thread on the giving wheel 11. The drive 19 of the thread is made in the form of essentially straight line segment of the path of movement of the thread. To control the tension of the thread, a sensitive device 22 is provided, the measuring stroke of which is negligible compared to the length of the thread to be accumulated in the accumulator 19 of the thread. The measuring stroke is determined by the movable element 25 of the sensitive device 22 and is directed perpendicular to the path of movement of the thread. It is small and is less than 2 mm.

The connection has a low inertia of the drive device 9 with the drive 19 of the thread, using its own elasticity of the thread, and with a regulating device 24, tracking with the help of a sensitive device 22 for the tension of the thread. allows you to use the yarn feeder 1 to feed elastic yarn and maintain the yarn tension substantially constant, even with a very variable yarn consumption. Due to the fact that the thread 2 in the accumulator 19 of the thread does not change the direction of movement and, in particular, any significant friction, and due to the fact that the thread 2 hits the thread guide wheel 11 without intermediate impact of the thread brake, short reverse feeds can also be compensated the threads 2 from the knitting machine into the device 1 for feeding the threads with the help of a short reverse rotation of the thread-feed wheel 11.

Claims (21)

CLAIM 1. A yarn feeder for an elastic material for feeding yarn to the looping sites with a sudden time-varying yarn consumption for knitting and knitting machines, in particular, for flat knitting machines (4), containing threading means that define the thread path defined by the yarn guide elements, a yarn feed wheel, which is installed in the path of the thread so that it can be covered by the thread, and which serves to transport the yarn in certain modes, the electric motor, having a small moment of inertia, to Secondly, a sensitive device for measuring the tension of the thread is rigidly connected to the thread-bearing wheel, while the sensitive device has a thread guide element configured with at least a slight deviation along the measuring stroke, a control device with which the motor for driving the thread guide wheel is based on the signals generated by the sensitive device are controlled so that the thread tension is adjusted to the nominal value, the thread accumulator for the intermediate accumulation of the thread and, if necessary, for re-reception of the thread fed by the threading wheel and unspent at the places of looping, and for issuing the thread that is required at the places of looping, but which has not yet been filed by the threadbar, characterized in that the drive (19) of the thread is made functionally separate from the sensing device (22), and the entire path traveled by the thread is made inelastic, the sensing device (22) is made with a measuring stroke that is essentially zero, and the drive (19) of the thread is formed by a segment put and between the thread on the giving wheel (11) and the looping point, on which the elastic thread (2) is held with the possibility of free stretching, and the thread accumulator has such a length that the thread segment in the accumulator has a stiffness coefficient which is less than the specified limit value, equal to the ratio of the maximum change in force to the length of the thread, which the maximum can accept the accumulator of the thread. 2. The use of a section of the path of movement of the thread of the yarn feeder for an elastic material, which is provided for feeding the yarn to the places of looping with a sharply varying in time consumption of the yarn in knitting and knitting machines, in particular in flat knitting machines (4), and which contains threading means, which define the path of the thread, defined by rigidly installed thread guiding elements, the thread-giving wheel, which is installed in the path of the thread so that it can be covered by the thread, and which serves as a transport yarn in certain modes, an electric motor having a small moment of inertia, which is rigidly connected to the yarn guide wheel, a sensitive device for measuring the tension of the thread, while the sensitive device has a yarn guide element with at least a slight deviation along the measuring stroke, and a control device with which the motor for driving the thread guide wheel, based on the signal delivered by the sensitive device, is controlled so that the tension is not and is adjusted to be set to the nominal value, as a yarn accumulator for receiving, intermediate accumulation and yarn output, which with sharp fluctuations in the thread tension due to moments of inertia of the threading wheel and the engine is supplied in excess or insufficient quantity compared to the thread consumption in the knitting machine, with This forms a segment of the path between the thread-giving wheel (11) and the place of looping, on which the elastic thread (2) is held with the possibility of free stretching, and the stretch of the path is length, that is in the storage section of the filament has a spring constant which is smaller than a predetermined limit value, which is the ratio of maximum force to change the length of the thread which can accept a maximum thread drive. 3. Thread feeder in π. 1, characterized in that the sensing device (22) is in contact with the thread (2) element (25), having a maximum stroke that is at least one order of magnitude smaller than the length of the thread (2) to be intermediate accumulation and be located in the drive (19) thread. 4. Thread feeder in π. 1, characterized in that the sensing device (22) has a spring tongue (51), the bending of which is determined by the tension of the thread and which is connected to a transducer for measuring the bend. 5. The feeder thread according to claim 4, characterized in that the transducer is an electromechanical transducer with a small required deviation. 6. Thread feeder in π. 1, characterized in that the sensing device (22) is made structurally separately from the rest of the device (1) filing threads. 7. Thread feeder in π. 1, characterized in that the sensitive device (22) has a separate suspension, which is made so that the connection with the oscillatory movement of the knitting machine (4) is eliminated. 8. Thread feeder in π. 1, characterized in that it is protected from the oscillatory movements of the knitting machine (4). 9. Thread feeder in π. 1, characterized in that it has a regulating device (24) for controlling the drive device (9) in all modes of operation, regardless of the speed of the knitting machine (4), based on the thread tension determined by the sensitive device (22). 10. Thread feeder according to claim 9, characterized in that the regulating device (24) is a proportional-integral regulator. 11. A filing device according to claim 9, characterized in that the regulating device (24) is an integral-differential proportional proportional controller. 12. Thread feeder in π. 1, characterized in that the drive device (9) is a stepper motor. 13. Thread feeder in π. 1, characterized in that the drive device (9) is an electric motor with a disk rotor. 14. Thread feeder in π. 1, characterized in that the driving device (9) and the corresponding control circuit (regulating device 24) are made to ensure the operation of the driving device (9) in two directions of rotation. 15. A yarn feeder in accordance with claim 1, characterized in that the yarn feed wheel (11) is formed by radially arranged wire brackets (13) fixed on the hub (12), each of which has a section extending essentially in the axial direction (16 ) for laying the thread, each wire clip (13) has two needles (14, 15), on which the axial section (16) rests. 16. A yarn feeder according to claim 1, characterized in that the thread path from the yarn feed wheel (11) to the yarn guide of the machine element (6) of the knitting machine (4) passes essentially without changing the direction of movement. 17. The yarn feeder according to claim 1, characterized in that to determine the current value of the tension of the thread, two independently operating sensing devices (22, 22 ') are provided, which are located at a distance from each other along the path of the thread. 18. Thread feeder according to claim 1, characterized in that a filter (29) is located between the sensing device (22) and the regulating device (24) connected to it. 19. Thread feeder according to and. 18, characterized in that the filter (29) suppresses the frequency of interference. 20. A filing device according to claim 1, characterized in that the sensing device (29) is equipped with compensating means for suppressing interference signals. 21. Use of a yarn feeder in one or more of the preceding paragraphs for a flat knitting machine.